MMP1 and rheumatoid arthritis: The proinflammatory cytokines in the joints stimulate the local production of MMPs and aggrecanases, which can degrade all components of the cartilage ECM, for instance during inflammations such as OA and RA [34] Mehana, 2019 #285; [22] The cellular origin and properties of different MMPs vary, and those that mainly have been implicated as produced by chondrocytes are MMP-1, -3 and -13.